It comes in a small teal box with a label that says "New Boomerang Pet Ball. Really Works!," with the word "new" imprinted in light green text within a dark green explosion banner, the words "boomerang pet ball" in white text within a dark red wide diagonal line across the box, and the words "really works" in yellow text within a small brown line.
The ball itself is a boomerang, hence the name. It can be thrown and returns to whoever threw it.
Role in episode
When SpongeBob attempts to get Gary to take a bath, he throws the ball towards the bathtub. However, the ball bounces back. Later, SpongeBob throws the box, but it bounces back at his head when he begins to walk away.